Distillation of tar



Nov. 22, 1932. s. P. MILLER DISTILLATION OF TAR Filed March 15, 1927 4 Sheets-Sheet INVENTOR ATTORNEYS Nov. 22, 1932.

s. PQMILLER DISTILLATION'OF TAR Filed Maron 15. 1927 4 sheets-sheet 2 Z; M f fz'g. i 24 1 7/2 23 A Y 7/"1/7 /v9 T 29 2 E; 0 8 H7 ,5 :f5 i l 6g l /3 f *i INVENTOR /'M/L? ATTORNEYS Nov. 22, 1'932. V5 p, M|| ER 1,888,236

DISTILLATION OF TAR Filed March 15, 1927 4 Sheets-Sheet S' Figi INVENTOR W ATTORNEYS Nov. 22, 1932. s. P. MILLER DISTILLATION OF TAR- Filed March 15.

KM. Nm.

ATTORNEYS 'Y Patented Nov. 22, 1932 `UNITED STATESv PATENT ori-ICE STUART PABMELEE MILLER, .OF TENAFLY, NEW JERSEY, ASSIGNOB TO THE BARRETT COMPANY, NEW YORK, N. Y., A CORPORATION OF NEW JERSEY DISTILLATION OF T AB Application led Iarchllli, 1927. Serial No. 175,480.

'lhis invention relates to improvements in the distillation of tars, and particularly to the utilization of the heat available in the gases produced in coal carbonization plants such as coke ovens to distill tar and to produce oils and pitches by such distillation. The invention Will be described especially withreference to its application to coke ovens.

In the ordinary operation of by-product coke ovens the gases producedby the coking operation pass from the individual ,ovens through uptake pipes and goose-necks to a collector main or mains common to a number of the ovens of the battery. The gases, commonly known as foull gases, leave the ovens at high temperature, e. g., 600 to 700 C. or higher, and carry the volatilized tars and oils resulting from the distillation of the coal.

Ordinarilythe gases are cooled as rapidly as possible by the application of sprays of ammonia liquor or ammonia liqu'or and tar in the goose-necks and collector main, the heat in the gases being thereby dissipated. The rapid cooling of the gases causes separation of tar containing the heavier oils in the co1- lector main. Further cooling is effected in the cross-over main which connects the collector main to the condensing system and in the cooling or condensing system, and an additional quantity of tar carrying both heavier `and lighter oils is thus separated. Thecollectcd tar is shipped from the coke-oven plant to a tar-distillation plant for distillation and separation of the oils and the production of pitches of i-'arying qualities. Handling losses, freight charges and distillation costs, including fuel and capital and maintenance exf penses for the special equipment required for distillation. add to the cost of production of the end products of the distillation.

It is an object of the present invention to provide a method and apparatus which permit the distillation of tar at the coke-oven plant, the utilization of the heat of the cokeoven gases Jfor that purpose, the operation of the collector main in an improved manner to avoid objectionable ,formation or deposit oi' solid hard pitch therein and the production of pitches having the various qualities and characteristics required by the trade and aninereased proportion of oils as a result of the distillation.

According to the` present invention the heat of the coke-oven gases is utilized in two suc cessive operations to. distill 'tar and to separate vaporizable oils therefrom, iirst, by spraying or otherwise bringing the tar into intimate contact with the hot coke-oven gases preferably immediately after the gases leave the ovens, and, second, by bringing additional tar, etc. intointimate contact with the gases, e. g., in the'collector main, to utilize a urther amount of the heat of the gases for tar distillation.

The spraying of tar into the hot coke-oven gases in successive o erations resultsin cooling of these gases rom the temperature at which they normally escape from the coke oven to successively lower temperatures. The extent to which the gases are cooled and the corresponding amount of distillation accomplished in each case will depend upon the amount, character and temperature of tar supplied, the intimacy and the time of contact-of the tar spray with the gases.

-The first use of the gases for distillation can be made satisfactorily in a distillation apparatus which may, for example, have the form of an uptake-pipe still, that is to say, a suitable chamber may be provided directly above one or more uptake pipes leading from the ovens ofthe coke-oven battery into which tar can be sprayed and thuf` brought into intimate contact with the hot gases directly after the latter leave the ovens,l full advantage being taken thereby of the high temperature of the gases at t is point.` The still or stills so employed may be arranged to' receive the tar to be distilled continuously through the spray nozzles therein and the pitch resulting from the distillation can be Withdrawn and recirculated if desired to effect a further distillation and the production of harder pitches. disclosed and claimed in the application of George E. Brandon, Serial No. 154,746.

The gases escaping from the still, together with the vapors resulting from the distillation, pass into the goose-necks leading to the collector main at relatively high temperature Such an uptake still is'- and are there again utilized for distillation of tar or oil.

Diiiiculty in the collector main can be avoided during this second distilling operation by eliminating or limiting the amount of ammonia liquor sprayed into t-he goosenecks and collector main and by substituting therefor hot tar or oil in quantity sufficient to rapidly reduce the temperature of the gases to the desired point. More or less distillation of the tar or oil thus introduced will be effected and the vapors thus produced will join the vapors and gases fiowing through the collector main. The volume of tar or oil introduced to the collector main should be suffieient to prevent the formation therein of undesirable accumulations. The tar Withdrawn from the collector main accordingly may be a partially distilled tar of desired composition. The extent to which distillation may be carried in the collector main will vary depending on the design of the particular apparatus employed, but in general is limited so that objectionable pitch accumulations are not formed in the apparatus.

Such partially distilled tar can be subjected thereafter to further distillation by intimate contact with the hot coke-oven gases in the uptake stills immediately after the gases leave the ovens to distill further quantities of oil therefrom and to produce pitches having the desired characteristics, the distillation of the tar thus being a two-stage distillation.

The tar or oil may be introduced to the collector main through spray nozzles as hereinbefore described or it may be supplied at one end of the main and permitted to flow therethrough. The tar or oil can be withdrawn either continuously or intermittently as desired and it may be recirculated to effect the cooling of additional quantities of the coke-oven gases and to accomplish further distillation of the tar or oil. The important considerations in connection with the operation of the collector main as described are the intimate distribution of the tar or pitch in the coke-oven gases and thewashing or flushing of the surfaces of the collector main with the hot tar yso that accumulation of solid hard pitch thereon is prevented and the pitch carried away with the tar flowing through. the bottom of the collector main.

The intimate mingling of the tar with the hot gases in the collector main can be accomplished in various ways, for example, by the provision of the spray nozzles through which all or a portion of the tar is introduced to the collector main. It 'can be accomplished likewise by agitation of the tar in the collector main, for example, by the provision of a shaft or shafts carrying paddles and actuated so that the paddles violently agitate the tar and throw particles thereof into the stream of gases flowing through the collector main and onto the exposed surfaces of the wall of the collector main so that the latter is constantly flushed with the hot tar. Rotating cones or other agitating means can be similarly employed and gases such as fuel gases, cokeoven gases or steam can be introduced through perforated pipes or through suction Ts (McDaniel type ejectors) immersed in the tar which is thrown upwardly by the gases introduced under pressure and thus distributed in the stream of coke-oven gases passing through the collector main.

Although indiscriminate cooling of the gases in the collector main as heretofore practiced is4 tobe avoided it may be desirable to introduce limited quantities of water or ammonia liquor with the tar which is sprayed into the collector main to cool the gases to a predetermined and regulated extent. The regulation of the cooling effect can be accomplished readily with water because of the high specific and latent heats of water and its low boiling point as compared with tar and oils. It is possible, therefore, to add water or ammonia liquor in proportion required to remove the excess heat not needed for the distillation of the tar.

It is to be understood that one of the purposes of introducing tar into the collector main is the further cooling of the cokeoven gases therein and-the avoidance of the formation of solid hard pitch therein. The amount of tar or oil introduced to the collector main should consequently be regulated to accomplish this purpose. Some distillation will, however, be effected by the absorption of heat from the hot coke-oven gases. This distillation effects an enrichment in the gases passing through the main in vapors of oils distilled from the tars, and is a valuable preliminary treatment of the tar prior to its further distillationin the uptake stills.

The distilling capacity of the gases from a single coke-oven battery is greatly in eX- cess of that required for the distillation of the amount of tar which a single coke-oven battery produces so that the tar from a considerable number of coke-oven batteries can be distilled by hot gases from a single battery. Where the amount of tar available for distillation is limited, it is advantageous to operate a few uptake stills in connection with a short collector main separate from the usual collector main and to conduct the distillation of tar preliminarily to the further distillation thereof in the uptake stills in the short collector main, the usual collector main being operated then in the customary manner by the introduction of 'sprays of ammonia liquor or ammonia liquor and tar.

The short collector main can be disposed above, below, or alongside of the usual collector main-v or it maybe placed at the rear of the battery together with the uptake stills with which it is connected. In that ease all of the ovens of the battery will be connected through the usual uptake pipes and goose-necks to the usual collector main and valves will be provided to permit operation of the ovens in the usual way or to divert a portion ofthe hot coke-oven gases through the uptake stillsand short collector main in which tar is circulated in the manner here- Y inbefore described.

The tar which is distilled according to the multiple-distillation process of the present invention may be tar produced at the same coke-oven plant or at 'another plant. It may contain all or practicall all of the condens-l able oils or it may be a eavy tar containing It may be a heavy tar,

, distilled separately at the coke-oven plant or they can be admixed in suitable proportions and can be distilled together giving directly a composite pitch product. For e'xample, horizontal gas-retort tar with high free carbon content can be admiXed with coke-oven tar and the mixture ycan be distilled to give a composite pitch higher in free carbon than the pitch from the coke-oven tar and to give a composite oil distillate.. The distillation' of such composite or admixed tars can be effected in a counter-current manner by subjecting them 'rst to distillation inthe collector main by gases at a lower temperature and then in the uptake stills by gases at a higher temperature.

Tar as commonly produced and collected at coke-oven plantsrcontains more or less water or ammonia liquor admixed therewith. Such tar can be employed directlyand dehydrated as well as distilled in the collector main, and thenfurther distilled in the uptake still or stills. The tar can, if desired, be preheated in any suitable manner to 4reduce it to a thinly fluid state which will facilitate the spraying of the tar into the hot cokeoven gases and will increase the capacity of the gases for distilling the tar although the amount of heat contained in the hot cokeoven gases is so great that yelfective dehydration as well as distillation can be ei'ected Y and preheating of the tar by separate preheating means may not be necessary. One of the advantages of the present invention is the possibility of effecting the dehydration of the tar as it circulates through the collector main. being thereinsubjected to a sufiiciently high temperature to remove all of the water together with'the lighter oils. The tar can then be=delivered in a preheated state to the uptake stills entirely free from water* and subjected therein .to further distillation for they purpose of producing pitches of the desiredcharacter.

In addition to producing pitches of difierentproperties and characteristics, the present lnvention permits the production of distillates of various kinds from tar or tar fractions -or oils, and different t'ars or oils can be simultaneously distilled, e. g., by distilling oil or tarry oil in the collector mainand tar in the uptake stills. The distillation of oil can be effectively conducted in the collector main where the gases at lower temperature carry nevertheless sucient heat to accomplish its distillation. The tari-y residue from such oil joins the tar which is circulated through the collector main and may be eventually delivered tothe uptake stills for further distillation in the manner described. The gases escaping from the collector main carry most of the oilvapors produced in the uptake stills, where these are not separately collected, and also the vapors produced by the distillation effected in the collector main. These gases although partially cooled by contact with the tar or. oil inthe collector main, as well as by the distillation of the tar inthe uptake stills, are, nevertheless, relatively hot so that the oils are largely retained in vapor form. The gases carrying the 'vaf pors are withdrawn and may be subjected to any subsequent desirable treatment, for the purpose' of condensing the oils in fractions. Preferably the gases are conducted through a cross-over `main to cooling apparatus. They may/be cooled in the cross-over main and the condensate thus produced 'can be withdrawn.

Instead of cooling the gases and vaporsv rapidly, they may be cooled progressively to effect the fractional condensation of the The largeincrease in condensable vapor content of the gasesv due to the distillation -of tar and oil results in the recovery of a greatly increased amount of light tar and oil products which, together with the scrubbing and purifying effect of the tar and oil on the gases, gives relatively cleaner oil products than with ordinary byproduct condensing systems.

Where a separate short collector, main is used in conjunction with the uptake stills, a

j separate condensing system may be employed.

Thus, instead of mingling the o il vapors iesulting from distillation of tar with the.

gases which are not utilized for distillation I purposes, the oil vapors may be cooled and condensed separately, preferably in frac-l tional Condensers, while thegases from the usual collector main'are subjected to cooling and condensation in the ordinary condensir'lg'A system. Likewise, where one of several mains of a battery is used for distillation the gases from that'main may be kept separate bringing the tar or oil into direct contact' lin the drawings, in which and may be separately cooled for recovery of oils.

' The present invention is of more or less Ygeneral application to the distillation of. tar and .oils and the recovery f d istillates.e vrihe invention involves utilization of the. cokeoven gases in ,a series of successive o erations for the distillation of tar or oil by therewith in the successive distilling operaations, which operations may be countercurrent.

The invention will be further illustrated by the following more detailed description I which should be read with the accompanylng drawings showing apparatus embodying the invention and adapted for the practice thereof but it is intended and will be under- Y stood l ing the application of mechanical agitators in the collector main; and

Fig. is a plan view of a portion of the coke-oven battery showing the application of the uptake stills with a separate short collector main.

Referring to the drawings, 5 indicates a battery of coke ovens having individual uptake pipes and goose-necks 6 which connect the ovens with a collector main 7. The latter may be of any usual forni and construc, tion and is designed to receive all of the gases from the individual coke ovens and to deliver them through a centre box 8 to a cross-over main 9 which is connected to the condensing apparatus hereinafter described. The collector main and the goose-necks leading thereto are provided with spray nozzles 1() and 11 and the latter are connected by pipes 12 to a pump 13 which is adapted to force tar or oil under the necessary pressure into the spray nozzles for the purpose of disseminating the tar in finely divided form in the collector main. The tar may be drawn from any suitable source such as a tank 14. The tar or oil may also be introduced to the collector main through a pipe 15 to ensure the maintenance therein of a suflicient volume of the tar or oil to prevent the formation or accumulation of solid hard pitch in the main. rl`he tar or oil c an be recirculated if'desired through a pipe 1G and pump 17 and the tar or oil can be withdrawn either continuously or intermittently through a pipe 17. y

rlhe cross-over main 9 which receives the gases Iand vapors Vfrom the collector main `purpose of distilling tar.

vmay. be connected `through a pipe 18 to a decan'ter 19 so that the condensate in the crossover main 'can be withdrawn." The tar or oil produced in the .cross-over-main is thus separated from the' ammonia liquor. The ammonia liquor can be treated in any suitable manner for the recovery of ammonia therefrom and the tar can be delivered tol the tank 14 from which it may be introduced tothe collector main for the purpose hereinbefore described.

The gases from the cross-over main may be conducted through the condensers 20 in which further cooling is effected to separate oils therefrom.- The oils may be Withdrawn .to a

densers in which the vapors are cooled progressively to predetermined temperatures for the purpose of separating the oils in separate fractions may be substituted for the condensers shown.

One or more uptake stills may be connected to the selected ovens l of. the battery for the These stills may comprise casings 23 supported above the ends of the usual uptake pipes and being provided with one or more spray nozzles 24 connected through pipes 25 to a source of tar.

The tar to be introduced to the uptake stills is preferably that which has been previously `subjected to the heating effect of the cokeoven gases in the collector main and the tar may be withdrawn directly from the collector main and Adelivered through a, pump 26 to the pipes 25 or the tar can be stored in a suitable tank 27 and delivered to the uptake stills as required. Baiiles 28 are provided .within the uptake stills to prevent tar from entering the coke ovens.

. The tar in finely divided form is intimately p provided to `preventftar from passing into the ovens through the uptake pipes.

By proper regulation of the amount of tar introducedits temperature and the time during which it remains in contact with the hot scribedand adapted to be supplied with tar pitch thereon.

coke-oven gases in the uptake still, the degree of distillation and consequently the amount of oil distilled from the tar and the characteristics of the pitch produced can be controlled. It is possible, therefore, to produce pitches of the kind required directl as the result of the distillation in the u ta e stills and at they streamof gases\pass ing therethrough and onto the collector main surfaces. Thus thedesired intimate contact of the tar with the gases is effected and thewalls of the collector main are flushed continuously with the hot tar to prevent accumulations of solid hard In Fig. of the drawings a modification of the invention is illustrated inwhich the ovens of the battery 32 are connected by uptake pipes and goose-necks 34 to a collector-.main 35 #from which the gases are conducted through a cross-over main 36 to condensers 37 or other means for separating the cxondensable products -from the gases which are withdrawn through an exhauster 37. The collector main in this case is designed to be operated in the usual' manner and is` provided, therefore, with spray nozzles to permit the introduction of ammonia liquor or ammonia liquor and tar into the collector main and the goose-necks leading thereto'.

l yAt the rear of the battery a number of the ovens' are connected to uptake stills 38 of the construction, for example, hereinbefore de'- for distillation by intimate contact with the hot coke-oven gases directly after the latter leave the ovens. The uptake stills areconnected through goose-necks 39 to a short col- -lector main 40 which is designed to be operated in the manner hereinbefore 'described A. by the circulation of tar therethrough for the effecting purpose of cooling the gases and a partiai distillation of the' tar. The collector main 40 is provided, therefore, with spray nozzles 4l which are supplied with tar 'through a pipe 42 from any suitable source such as a tank 43, a pump 44 being provided to introduce the tar under a suiiicient preszure. rfar can also be introduced to the short :ollector main through a pipe 45 to ensure rhe presence of a suflicient volume of tar in *he main. rlhe tar can be circulated through 'She main by means of a pipe 46 and pump 47 and tar can be withdrawn continuously 5r tar or oil to intermittently from the main through a pi e 48. rlhe tar thus circulated through t e" main and partially distilled by intimate contact with the hot coke-oven gases is delivered preferably to the uptake stills for further distillation and conversion into pitch, the vapors distilled therefrom being delivered to the short collector main and mingled with the vapors produced by the partial distillation therein of the tar which is delivered to the collector main. `In this way a two-'stage counter-current distillation of the tar is effected by the hot gases. -The gases carrying the oil vapors can be withdrawn through a, cross-over main 49 and delivered to a condensing system which may 1 include a number of fractional condensers 50 in which the gases are reduced progressively to lower temperatures at which fractions of the oils condense. The condensate can be withdrawn and utilizedfor the purpose for which such oils are useful in the trade. The remaining gases can be delivered through a pipe 51 to the exhauster 37 and thence conveyed with the remaining gases from the oven through the byproduct recovery system. f

As in the preceding embodiment -of the invention, it is important to flush the short collector main with a suflicient quantity -of prevent deposit of solid hard pitch therein. Only the lighter oils may be removed from the tar in the short collector main and the'distillation of the resulting tar for the production of harder pitch may be completed in the uptake stills. The supply of tar to the collector main can be regulated to accomplish this purpose. e

The advantages or" the invention have been set forth in some detail and the preferred embodiments have been described. It is to be understood, however, that various chan-ges may be made in the form and arrangement of the apparatus and in the operation as described without departing from the invention or sacrificing the advantages enumerated or f any other advantageous results-which may be accomplished by the application of the principles set forth. f

claim: o l. The improvement in the distillation of tar and production` of with the distillation of coal in a coke oven, which comprises spraying tar into hot cokeoven gases immediately after withdrawal thereof from the coke oven to distilll the tar and produce pitch, thereafter subjecting the gases to intimate contact with tar in volume suflicient to e'ect substantial coolingoi" the gases with only a'limited distillation of the tar and further coolingv the gases and vapors carried thereby to recover condensable constituents.

2. The improvement in the ldistillation of tar and production of pitch in combination pitch in combination With the distillation of coal'in a coke oven which comprises spraying tar into hot cokeoven gases immediately after withdrawal thereo from the coke oven to distill the -tar and produce pitch, thereafter subjecting the gases to intimate contact with tar in volume suiiicient to effect substantial cooling of the gases with only a limited distillation of the tar, and subjecting the tar thus partially disstilled to further distillation. by sprayin it into the hot coke-oven gases at the hig er temperature. y

3. The method of distilling tar in hot coal distillation gases resulting from the distillation of coal in a plurality of coke ovens, which comprises bringing the fresh hot coal distillation gases into contact with tarwhich has been sub`ected to a preliminary distillation and com ining the streams of gases from severalovens so as to form a continuous stream of hot gases enriched with oiltvapors resulting from the tar distillation, and then usin this stream of enriched gases for the preliminary distillation of the tar by continuously spraying the tar to be distilled into it .In testimony whereof I aiix my signature.

STUART PARMELEE MILLER.- 

